Radio receiver



July 22, 1941. B. LONG 2,250,268

RADIO RECEIVER Original Filed Oct. 1-, 1926 r\ n Ill [NVE/V TOR MB. LONG A 7' rak/vty Patented July 22, 1941 RADIO RECEIVER Maurice B. Long, Glen Ridge, N. J., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Original application October 1, 1926, Serial No.

138,854, now Patent No. 1,945,557, dated February 6, 1934. Divided and this application March 11, 1930, Serial No. 434,985. In Canada September 20, 1927 19 Claims.

This invention relates to radio receivers and particularly to control systems therefor.

This application is a division of my previous application, Serial No. 138,854, filed October 1, 1926, Patent No. 1,945,557 of Feb. 6, 1934.

An object of the invention is to prevent the operation of devices which are employed for controlling radio receivers from setting up harmful and undesirable disturbances in the output of the receivers.

In a specific embodiment of the invention, in a radio receiver in which a plurality of tuning condensers are selectively controlled by relay circuits to permit the automatic tuning of the receiver to any one of the desired number of Wave lengths, there is provided a master relay for disconnecting the loud speaker from the receiver while the tuning relays are being operated, so that electromagnetic and other disturbances set up by the operation of the relays will not affect the loud speaker.

The invention is not limited in its application to circuits for controlling the tuning or to control circuits employing relays but may be used with circuits for controlling any characteristic of a receiver or to other types of control circuits, for example, those using motors. Furthermore, in order to render the loud speaker inoperative, it may be short circuited instead of being disconnected. This and other modifications and uses are within the scope of the invention as will appear from the appended claims.

The invention will be more readily understood by reference to the following detailed description in connection with the drawing which shows a circuit diagram of one embodiment of the invention.

In the circuit shown in the drawing there is an antenna circuit, comprising an antenna 5, an inductance 6, and three optional or alternative paths to ground from inductance 6. Relays l and 8 controlled by keys or push buttons 9, H), H and I2, are adapted to connect any one of the three paths in the antenna circuit. Of these paths, one includes a variable condenser I and a coil l8, the second includes a variable condenser l6 and a coil I9, and the third includes a variable condenser l1 and a coil 20. These three coils constitute the primary windings of a coupling coil 2|, the secondary winding 22 of which forms part of the tuned input circuit of a radio receiver. This input circuit may be tuned by any one of three condensers I5, I 6 and H which are optionally connected in circuit by the relays 'l and 8 under control 'of the keys 9, l0,

l and [2. The radio receiver comprises an electric space discharge detector tube 24 feeding an electric space discharge amplifier tube 25 through an audio frequency transformer 26 and the left-hand contact of relay 21, an electric space discharge amplifier tube 28 fed from tube 25 through an audio frequency transformer 29, and a loud speaking telephone receiver 30 fed from tube 28 through a transformer 3|, the right-hand contact of a relay 32 and an adjustable volume control or voltage changing device 33. As indicated by conductors 34, other volume control devices and loud speakers may be connected to the output side of transformer 3| and located at any desired places.

A battery 49 supplies filament heating current for tubes 24 and 25 through the left-hand inner contact of a relay 42, left-hand contact of relay 32, filament of tube 25, filament of tube 24, and a resistance 45. Steady potential for the grid of tube 25 is supplied by the voltage drop in the filament of tube 24 and in resistance 45.

An alternating current source supplies current to the primary winding of a transformer 47. Current is also supplied from source 46 to the primary windings of transformers 48 and 49 through the right-hand outer contact of relay 42. The secondary winding of the transformer 41 supplies current for operating relays l, 8, 42 and 32 through keys 9, H], H and I2.

A secondary winding 50 of transformer 48 has its mid-point grounded and supplies alternating current for heating the filament of tube 28.

Alternating current from a secondary winding 5| of transformer 48 is rectified in .a circuit extending from winding 5| through choke coil 52, resistances 55, 56 and 51 to earth, thence through conductor 60, resistance 65, conductor 66, the space discharge path of an electric space discharge rectifier tube 61, to winding 5|. A portion of winding 5| supplies alternating current for heating the filament of rectifier tube 61. The voltage drop in resistance is applied as steady potential to the grid of tube 28, through a resistance 68 and the secondary winding of transformer 29.

The voltage drop across resistance 5'! is applied to the plate of tube 24, through the primary winding of transformer 26.

The voltage drop across resistances 56 and 51 is applied between the plate and the filament circuit of tube 25, through the primary winding of transformer 29.

The voltage drop across resistances 55, 56 and 51 is applied between the plate and the filament circuit of tube 28, through the primary winding of transformer 3 I.

The choke coil 52 and the condenser l9 reduce voltage fluctuations across resistances 55, 55, 51 and 65. A condenser H further reduces voltage fluctuations across resistances 55, 56 and 51, a condenser 12 further reduces like fluctuations across resistances 56 and 51, a condenser 13 produces a similar result across resistance '5. sistance 68 and a condenser i4 further reduce voltage fluctuations applied from resistance 65 between the grid and the filament of tube 28, without substantially reducing the steady voltage applied from resistance 65 to that grid. Condensers ll, 12-, and 13 also provide paths of low impedance to signaling currents in the plate circuits of tubes 28, 25 and 24 respectively.

As indicated by the broken lines representing conductors leading from the set of keys 9, l9, II and I2, this set of keys may be, if desired, remote from the condensers i5, i6, ll, l5, l6 and H, the connection of which to the receiver circuit they control. For example, this set of keys may be located with a loud speaking telephone receiver (not shown) connected to the conductors 34 at a distance from the condensers, the tubes 24, 25 and 28 and the loud speaker 33. As indicated by conductors 'l5,other sets of keys (not shown) like the set constituted by keys 9, Ni, ii and I2 may be employed, the keys 9, l3, H and 12 being connected in multiple with the corresponding keys, respectively, of each of such other sets. Such other sets may be located at any desired places. For example, one set may be near the tuning condensers and the loud spaker Pilot lamps such as [6 are connected to the secondary winding of transformer 49, the primary winding of which is connected directly in parallel with the primary winding of transformer 48. Each of these lamps may be located at any desired place and indicates whether the source 46 is supplying E. M. F. to the transformer 48,

The armature of each of the relays l, 8 and 42, in the absence of current in the windings of the relay, is held in the position to which it was last operated by' one of its windings. A holding spring is shown for each of these relays, as representing means for thus holding the armature. The winding of relay 32 is connected directly in series with the secondary winding of transformer 41. Relay 32 is therefore momentarily operated whenever one of the keys 9 to i2 is momentarily operated or, in other words, whenever either of the windings of relaysv 1, 8 or 42 is energized. In operating, relay 32 quickly opens its right-hand contact, to disconnect from the secondary winding of transformer 3| the volume control devices and loud speakers such as 33 and 35, and thereafter opens at its left-hand contact the filament heating circuit of tubes 24 and 25. In closing, relay 32 first closes its left-handcontact and thereafter closes its right-hand contact. The operation of the relay 32 prevents the production of noise in the loud speakers due to the action upon the input circuits of tubes 24 and 25 of stray fields from the windings of relays 1;8 and-42 when those windings are switched in'o'r out of circuit by keysS to 12. The relay opens the cir- V cuit of the secondary winding of transformer 3! before the stray field has timeto change materially; and the cooling of the filaments of tubes 24 and 25 due to the opening of the filament circuit at relay 32 renders the tubes inoperative until the stray field has again reached a substantially steady state.

Each of the coils l8, l9 and 2G is, independently v closed momentarily. Thereupon, the left-hand winding of relay l, the right-hand winding of relay 42 and the winding of relay 32 are energized over a circuit extending from the secondary winding of transformer 4! through the winding of relay 32, key 9, a resistance l9, left-hand winding of relay 1, and right-hand winding of relay 42. Relay 32 operates momentarily. Relay 1 operates, or remains operated, to the left, remaining in that position after key 9 is released. Relay 42 operates, or remains operated, to the right, remaining in that position after key 9 is released. With relay 42 so operated, the filament circuit of tubes 24 and 25 and the circuit of the primary windings of transformers 48 and 49 are closed at its contacts. With relay 1 so operated, the antenna circuit extends from antenna 5 and coil 6 through the outer left-hand contact of relay l, condenser l5 and coil [8 to ground; and the inner right-hand contact of relay 1 connects condenser !5 across coil 22. Condensers l5, ll, 16' and. H and coils l9 and 20 are thus out of circuit. Now by adjusting condensers l5 and the system can be tuned to the wave length of, say, station J. Also, the'coupling between coils l8 and 22 maybe properly adjusted for the intensity of the waves received by antenna 5 from station J. The system is then conditioned for receiving signals from station J, and thereafter if the operator has changed it to a condition for receiving signals of other wave lengths or to a condition in which it is not responsive to signals of any wave length, it can be conditioned substantially instantaneously for receiving signals from station J by merely depressing key 9 momentarily.

, The system having been adjusted so that it can be set substantially instantaneously to receive selectively from station J, it may next be adjusted so that it can be set similarly to receive from station K. To so adjust it, key 10 is first closed momentarily. Thereupon a circuit is established momentarily extending from the secondary winding of transformer 41 through the winding of relay 32, key H), the left-hand winding of relay 8, the right-hand winding of relay 1, and the right-hand winding of relay 42. Consequently, relay 32 operates momentarily, and relays 1, 8 and 42 operate or remain operated to the right, the left and the right, respectively, remaining in those positions after key Ill is released. With the relay 42 so operated to the right, the filament circuit of tubes 24 and 25 and the circuit of the primary windings of transformers 48 and 49 are closed at its contacts. With relays l and 8 so operated, the antenna circuit extends from antenna 5 and coil 6 through the inner left-hand contact of relay l, the outer left-hand contact of relay 8, condenser l3 and coil IE! to ground; and condenser I5 is connected across coil 22 through the inner right-hand contact of' relay 8 and the outer right-hand contact of relay 1. Condensers l5, l1, l5 and I1 and coils I8 and 20 are then out of circuit. Now by adjusting condensers l6 and Hi the system can be tuned to the wave length of station K. Also, the coupling between coils l9 and 22 can be properly adjusted for the intensity of the waves received by antenna from station K. The system is then adjusted for receiving signals from station K, and thereafter, if the operator has changed it to a condition for receiving signals of other Wave length or to a condition in which it is not responsive to signals of any wave length, it may be conditioned substantially instantaneously for receiving signals from station K by merely depressing key I B, momentarily.

The system having been adjusted so that it can be set substantially instantaneously to receive selectively signals from station J or station K, it may next be adjusted so that it may be set similarly to receive from station L. To so condition it, key I I is first closed momentarily.

Thereupon a circuit is momentarily established, extending from the secondary winding of transformer 41 through the winding of relay 32, key M, right-hand winding of relay 8, right-hand winding of relay 1, and right-hand winding of relay 42. Consequently, relay 32 operates momentarily and each of relays l, 8 and 62 operates, or remains operated, to the right, remaining so operate-d after key I l is released. With the relay 42 so operated, the filament circuit of tubes 24 and 25 and the circuit of the primary windings of transformers 58 and 49 are closed at its contacts. With relays 1 and 8 so operated, the antenna circuit extends from antenna 5 and coil 5 through inner left-hand contacts of relays i and 8, condenser l'! and coil 20, to ground; and condenser IT is connected across coil 22 through the outer right-hand contacts of relays l and 8. Condensers l5, l5, l5 and I6 and coils l8 and 89 are then out of circuit. Now by adjusting condensers I1 and H the system can be tuned to the wave length of station L. Also, the coupling between coils and 22 can be properly adjusted for the intensity of the waves received from station L. The system is then adjusted for receiving signals from station L, and thereafter if the operator has changed it to a condition for receiving signals of other wave length, or to a condition in which it is not responsive to signals of any wave length, it may be conditioned substantially instantaneously for receiving signals from station L by merely depressing key it momentarily.

At any time, the system may be rendered unresponsive to signals of any wave length by depressing key I2 momentarily, whereby there is established momentarily a circuit extending from the secondary winding of transformer 4? through relay 32, key 52, a resistance 82, and left-hand winding of relay 42. Upon establishing this circuit, relay 32 operates momentarily, and relay 42 operates to the left to break the filament circuit of tubes 24 and and the circuit of the primary windings of transformers 48 and 29.

Thereafter, as indicated above, key 9, IE] or I I may be operated whenever it is desired to tune the system substantially instantaneously to the wave length of station J K or L, respectively.

Resistances 19 and 3!! enable each of the windings of relays l, 8, 42 and 32 to have the same constants and yet receive the same value of operating current from transformer 41, resistance 79 having an impedance substantially equal to that of one of said windings, and resistance 80 having an impedance twice the value of that of resistance 19.

The condensers E5, l5, l1, l5, l5 and I1 may a ing of relay 21, and switch 89 to battery 40.

be of any suitable type, as for instance, rotary plate, air dielectric condensers of ordinary type. One pair of these condensers may be varied or adjusted to tune the receiver to any desired one of a range of wave lengths, including the wave lengths of the stations to which the receiver is instantaneously tuned by the other pairs. This variation of the capacities of the one pair of condensers will not disturb the adjustment of the receiver for the instantaneous tuning by the other pairs, since the operation of a key for causing either of the other pairs to be connected in circuit causes the one pair to be withdrawn from circuit.

If desired, the constants of the antenna circuit or of the circuit fed thereby may be maintained fixed, the tuning of the receiver being accomplished by varying only one of these circuits.

A phonograph has a reproducer 86 and has start-stop mechanism represented, for example, by a brake 81. The start-stop mechanism when in position to prevent the motion of the phonograph turntable opens a switch 89 to maintain relay 21 deenergized. The grid or input circuit of tube 25 is then closed through transformer 25, at the left-hand contact of relay 21, in order that the radio receiver may be operated to reproduce radio signals received by antenna 5. When the start-stop mechanism is in position to allow the phonograph to operate, switch 89 is closed, and, provided relay 42 is closed to the right, relay 2! will be energized over a circuit extending from battery 45 through inner left-hand contacts of relay 42 and left-hand contact of relay 32, wind- This energization of relay 2'! disconnects the transformer 26 from the grid of tube 25, so that the radio receiver will not operate to reproduce radio signals received by antenna 5 during the time that the phonograph is operating. However, the radio receiver will automatically be rendered operative to reproduce the radio signals when the phonograph is stopped by the brake 81. The reproducer 86 is of the electrical type and is connected to the primary winding of a transformer 50, the secondary winding of which is adapted to be connected between the grid and the filament of tube 25 by a front contact on relay 21. Thus, when the phonograph is operating, its electrical output from reproducer 85 is amplified by tubes 25 and, 28 and converted into sound by the loud speakers such as 35.

What is claimed is:

1. In combination, signal indicating means, a tunable signal receiver for supplying any of a plurality of signals thereto, selectively operable electric means for controlling the tuning of said receiver to render it selectively responsive to any of said plurality of signals, relay means for rendering said indicating means inoperative, and a common control circuit for said electric means and said relay means.

2. In combination, signal indicating means, means for supplying any of a plurality of signals thereto, electric means for controlling the signal supplying means to render it selectively responsive to any of said plurality of signals, a source of current for energizing said electric means and a relay having a winding connected in series with said electric means and said source and adapted when energized to render said signal indicating means non-responsive to signals from said signal supplying means.

3. Remote tuning apparatus for a radio received to said translating apparatus, means for selectively tuning said input circuit for said different carrier channels, a series of relays for operating said selective tuning means, a control circuit for said series of relays, and additional relay means in said control circuit for disabling said translating means during the operation of said series of relays.

5. In combination, signal indicating means, meansior transmitting signals to said indicating means, said signal transmitting means comprising an electric space discharge device having a thermionic cathode, electromagnetically operated means for rendering said signal transmitting means operative, and means responsive to the operation of said electromagnetically operated means for momentarily rendering inoperative first said indicating means and then said thermionic cathode.

6. In combination, a radio receiver, selectively operable electromagnetic means for controlling the tuning of said radio receiver to render it selectively responsive to any of a plurality of radio signals, a loud speaker for reproducing the signals received by said receiver, and means for automatically rendering said loud speaker inoperative in response to any operationof said electromagnetic means.

7. In combination with a radio receiving set having a sound reproducer connected thereto, a switch in circuit with said sound reproducer, an electromagnet associated with the switch, selectively operable means for tuning the receiving set to any of a plurality of frequencies to render the sound reproducer responsive thereto and means associated with the tuning means to energize the electromagnet to cause the switch to render the sound reproducer ineffective in response to any tuning process whereby undesired sounds are prevented.

8. In combination, a signal receiver, electromagnetic means for controlling said signal receiver to render it selectively responsive to any of a plurality of signals, signal indicating means connected to said signal receiver and responsive to any of said plurality of signals, and means automatically operated upon the energization of said electromagnetic means to render inoperative said indicating means before the stray field set up by said electromagnetic means has built up to a sufiicient magnitude to produce a material disturbance in said indicating means and for maintaining said indicating means inoperative until said stray field has reached a substantially steady state.

9. In combination, signal indicating means, an electric discharge amplifier having a thermionic cathode and being connected to supply signals to said signal indicating means, means for supplying current for heating said cathode, electromagnetic means for controlling an operating condition of said amplifier, and means operated simultaneously with said eelctromagnetic means for disconnecting said signal indicating means from said amplifier and for cutting off the supply of heating current to said cathode.

10. Remote tuning apparatus for a radio receiver comprising selectively operable electromagnetic means for controlling the tuning of said radio receiver to render it selectively responsive to any of a plurality of radio signals, a loudspeaker for reproducing the signals received by said receiver, and means for automatically rendering said loud-speaker inoperative in response to any operation of said electromagnetic means.

MAURICE B. LONG. 

